From 451af504df0c62f695a69b83c250486e77c66378 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 13 May 2014 12:16:21 -0400 Subject: cgroup: replace cftype->write_string() with cftype->write() Convert all cftype->write_string() users to the new cftype->write() which maps directly to kernfs write operation and has full access to kernfs and cgroup contexts. The conversions are mostly mechanical. * @css and @cft are accessed using of_css() and of_cft() accessors respectively instead of being specified as arguments. * Should return @nbytes on success instead of 0. * @buf is not trimmed automatically. Trim if necessary. Note that blkcg and netprio don't need this as the parsers already handle whitespaces. cftype->write_string() has no user left after the conversions and removed. While at it, remove unnecessary local variable @p in cgroup_subtree_control_write() and stale comment about CGROUP_LOCAL_BUFFER_SIZE in cgroup_freezer.c. This patch doesn't introduce any visible behavior changes. v2: netprio was missing from conversion. Converted. Signed-off-by: Tejun Heo Acked-by: Aristeu Rozanski Acked-by: Vivek Goyal Acked-by: Li Zefan Cc: Jens Axboe Cc: Johannes Weiner Cc: Michal Hocko Cc: Neil Horman Cc: "David S. Miller" --- security/device_cgroup.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) (limited to 'security') diff --git a/security/device_cgroup.c b/security/device_cgroup.c index 9134dbf70d3e..7dbac4061b1c 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -767,27 +767,27 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup, return rc; } -static int devcgroup_access_write(struct cgroup_subsys_state *css, - struct cftype *cft, char *buffer) +static ssize_t devcgroup_access_write(struct kernfs_open_file *of, + char *buf, size_t nbytes, loff_t off) { int retval; mutex_lock(&devcgroup_mutex); - retval = devcgroup_update_access(css_to_devcgroup(css), - cft->private, buffer); + retval = devcgroup_update_access(css_to_devcgroup(of_css(of)), + of_cft(of)->private, strstrip(buf)); mutex_unlock(&devcgroup_mutex); - return retval; + return retval ?: nbytes; } static struct cftype dev_cgroup_files[] = { { .name = "allow", - .write_string = devcgroup_access_write, + .write = devcgroup_access_write, .private = DEVCG_ALLOW, }, { .name = "deny", - .write_string = devcgroup_access_write, + .write = devcgroup_access_write, .private = DEVCG_DENY, }, { -- cgit v1.2.2 From 5c9d535b893f30266ea29fe377cb9b002fcd76aa Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 16 May 2014 13:22:48 -0400 Subject: cgroup: remove css_parent() cgroup in general is moving towards using cgroup_subsys_state as the fundamental structural component and css_parent() was introduced to convert from using cgroup->parent to css->parent. It was quite some time ago and we're moving forward with making css more prominent. This patch drops the trivial wrapper css_parent() and let the users dereference css->parent. While at it, explicitly mark fields of css which are public and immutable. v2: New usage from device_cgroup.c converted. Signed-off-by: Tejun Heo Acked-by: Michal Hocko Acked-by: Neil Horman Acked-by: "David S. Miller" Acked-by: Li Zefan Cc: Vivek Goyal Cc: Jens Axboe Cc: Peter Zijlstra Cc: Johannes Weiner --- security/device_cgroup.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'security') diff --git a/security/device_cgroup.c b/security/device_cgroup.c index 7dbac4061b1c..ce14a31b1337 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -182,7 +182,7 @@ static inline bool is_devcg_online(const struct dev_cgroup *devcg) static int devcgroup_online(struct cgroup_subsys_state *css) { struct dev_cgroup *dev_cgroup = css_to_devcgroup(css); - struct dev_cgroup *parent_dev_cgroup = css_to_devcgroup(css_parent(css)); + struct dev_cgroup *parent_dev_cgroup = css_to_devcgroup(css->parent); int ret = 0; mutex_lock(&devcgroup_mutex); @@ -455,7 +455,7 @@ static bool verify_new_ex(struct dev_cgroup *dev_cgroup, static int parent_has_perm(struct dev_cgroup *childcg, struct dev_exception_item *ex) { - struct dev_cgroup *parent = css_to_devcgroup(css_parent(&childcg->css)); + struct dev_cgroup *parent = css_to_devcgroup(childcg->css.parent); if (!parent) return 1; @@ -476,7 +476,7 @@ static int parent_has_perm(struct dev_cgroup *childcg, static bool parent_allows_removal(struct dev_cgroup *childcg, struct dev_exception_item *ex) { - struct dev_cgroup *parent = css_to_devcgroup(css_parent(&childcg->css)); + struct dev_cgroup *parent = css_to_devcgroup(childcg->css.parent); if (!parent) return true; @@ -614,7 +614,7 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup, char temp[12]; /* 11 + 1 characters needed for a u32 */ int count, rc = 0; struct dev_exception_item ex; - struct dev_cgroup *parent = css_to_devcgroup(css_parent(&devcgroup->css)); + struct dev_cgroup *parent = css_to_devcgroup(devcgroup->css.parent); if (!capable(CAP_SYS_ADMIN)) return -EPERM; -- cgit v1.2.2 From 5877019d97ab827b808e8759c71ef8d31490907a Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 16 May 2014 13:22:48 -0400 Subject: device_cgroup: remove direct access to cgroup->children Currently, devcg::has_children() directly tests cgroup->children for list emptiness. The field is not a published field and scheduled to go away. In addition, the test isn't strictly correct as devcg should only care about children which are visible to userland. This patch converts has_children() to use css_next_child() instead. The subtle incorrectness is noted and will be dealt with later. Signed-off-by: Tejun Heo Acked-by: Aristeu Rozanski Acked-by: Serge Hallyn Acked-by: Li Zefan --- security/device_cgroup.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'security') diff --git a/security/device_cgroup.c b/security/device_cgroup.c index ce14a31b1337..084c8e417564 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -589,9 +589,17 @@ static int propagate_exception(struct dev_cgroup *devcg_root, static inline bool has_children(struct dev_cgroup *devcgroup) { - struct cgroup *cgrp = devcgroup->css.cgroup; + bool ret; - return !list_empty(&cgrp->children); + /* + * FIXME: There may be lingering offline csses and this function + * may return %true when there isn't any userland-visible child + * which is incorrect for our purposes. + */ + rcu_read_lock(); + ret = css_next_child(NULL, &devcgroup->css); + rcu_read_unlock(); + return ret; } /* -- cgit v1.2.2 From 7a3bb24f7c5ceebad19b12b66fd832a27a7e90df Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 16 May 2014 13:22:52 -0400 Subject: device_cgroup: use css_has_online_children() instead of has_children() devcgroup_update_access() wants to know whether there are child cgroups which are online and visible to userland and has_children() may return false positive. Replace it with css_has_online_children(). Signed-off-by: Tejun Heo Acked-by: Aristeu Rozanski Acked-by: Serge Hallyn Acked-by: Li Zefan --- security/device_cgroup.c | 19 ++----------------- 1 file changed, 2 insertions(+), 17 deletions(-) (limited to 'security') diff --git a/security/device_cgroup.c b/security/device_cgroup.c index 084c8e417564..d9d69e6930ed 100644 --- a/security/device_cgroup.c +++ b/security/device_cgroup.c @@ -587,21 +587,6 @@ static int propagate_exception(struct dev_cgroup *devcg_root, return rc; } -static inline bool has_children(struct dev_cgroup *devcgroup) -{ - bool ret; - - /* - * FIXME: There may be lingering offline csses and this function - * may return %true when there isn't any userland-visible child - * which is incorrect for our purposes. - */ - rcu_read_lock(); - ret = css_next_child(NULL, &devcgroup->css); - rcu_read_unlock(); - return ret; -} - /* * Modify the exception list using allow/deny rules. * CAP_SYS_ADMIN is needed for this. It's at least separate from CAP_MKNOD @@ -634,7 +619,7 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup, case 'a': switch (filetype) { case DEVCG_ALLOW: - if (has_children(devcgroup)) + if (css_has_online_children(&devcgroup->css)) return -EINVAL; if (!may_allow_all(parent)) @@ -650,7 +635,7 @@ static int devcgroup_update_access(struct dev_cgroup *devcgroup, return rc; break; case DEVCG_DENY: - if (has_children(devcgroup)) + if (css_has_online_children(&devcgroup->css)) return -EINVAL; dev_exception_clean(devcgroup); -- cgit v1.2.2